Portable drip containment device apparatus and method

ABSTRACT

A portable drip containment device comprises a tray formed of fuel and chemical resistant fabric. Side walls of the tray are supported by removable bolster segments formed of resilient open cell foam members enclosed within sleeves. The bolster segments are wrapped within a flap of material extending from under the side wall of the tray and around the bolster segments to secure them to the side walls. The outer edge or end of the flap is secured to the side wall. The bolstered side walls may be repeatedly driven across by industrial vehicles without harming the bolster or side wall. The modular bolster segments may be removed and easily stacked, and the tray folded and rolled into a compact modular form, for transport, storage, and reuse of the portable containment tray.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional Application of U.S. patent applicationSer. No. 13/850,834, filed Mar. 26, 2013 and entitled PORTABLE DRIPCONTAINMENT DEVICE APPARATUS AND METHOD, now U.S. Pat. No. 8,931,658,which is a Continuation of U.S. patent application Ser. No. 13/448,542filed, Apr. 17, 2012 and entitled PORTABLE DRIP CONTAINMENT DEVICEAPPARATUS AND METHOD, now U.S. Pat. No. 8,479,946, which claims priorityfrom U.S. Provisional Patent Application Ser. No. 61/495,141, filed Jun.9, 2011 and entitled PORTABLE DRIP CONTAINMENT DEVICE, by the sameinventor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to spill containment methods andmore particularly to portable apparatus for catching and containingspills of toxic or environmentally hazardous materials from industrialvehicles and related equipment.

2. Background of the Invention and Description of the Prior Art

In a number of industrial processes, machine equipment that includesapparatus that transports, dispenses, or utilizes materials—liquid ordry aggregate—that may be toxic to living things or otherwise harmful tothe environment requires some form of protective or containment deviceor method to avoid contamination thereof when the vehicle or othermachine is not in motion. In one example, machinery used for drillingoil and gas wells, especially those used in a process called hydraulicfracturing (often: “fracing”) presents a challenge to avoid spills onthe ground in such installations. In another example, loading orunloading chemicals on/from a vehicle, particularly in a remote orenvironmentally sensitive area, presents a need for a spill containmentdevice. Even though well-thought-out and carefully implementedprocedures for handling such materials may be in place andconscientiously used, accidents can and do occur that may result in harmto the surroundings where such equipment is located.

Constructing paved driveways or pads is one solution that enablesrelatively easy clean up of a spill. However, a paved surface is apermanent fixture that entails substantial expense to provide and thusis not suitable for machinery or installations where such equipment isused that is moved from place to place. Such is the case with oil andgas drilling machinery. Conventional forms of spill-containment devicesmay be constructed of light-weight fabric materials to provide devicesthat are portable and reusable. However, such materials, to provide forconvenient assembly and disassembly are necessarily flexible and someway to provide rigid side walls or fixed support for the non-rigidsidewalls is required. Various arrangements and configurations ofmechanical braces, collapsible or otherwise, or rigid or inflatable sidemembers, have been proposed to support the side walls of the containmentdevice. These have the disadvantage of requiring one or more ofrelatively cumbersome installation, assembly, adjustment, anddisassembly procedures in use, require tools during use, or require asource of compressed air, for example, to inflate supporting structuralelements of the containment unit.

What is needed is a containment method and/or apparatus having a minimumof components that can be easily installed, dismantled, and transportedfrom place to place, even to remote areas, and that may be reused in avariety of situations, yet provides a reliable barrier to spills uponthe surface of the ground.

SUMMARY OF THE INVENTION

Accordingly there is disclosed a portable drip containment device foruse under a vehicle that provides an advancement in the state of theart, comprising a tray formed of chemically resistant fabric and havinga floor panel and defined side walls of a predetermined heightsurrounding the floor panel; At least one wing flap extending outwardfrom an underside of the tray below each side wall; a deformable bolsterassembly surrounding the tray and removably attached to the side of eachside wall; wherein the bolster assembly is secured to each side wall bythe at least one wing flap wrapped around the bolster assembly disposedadjacent each side wall and attached to the upper edge of each sidewall.

In other aspects the bolster assembly is formed of a plurality ofelongated and deformable bolster segments formed of open cell foammembers individually enclosed in sleeves formed of the chemicallyresistant fabric and disposed end-to-end around the perimeter of thecontainment tray.

In another aspect a bolster member is formed of a resilient foammaterial preferably having a cross section shape selected from the groupconsisting of right triangle, rectangle, square, and other quadrilateralhaving at least one right angle corner.

In other aspects no braces or rigid or inflatable members are requiredto support the side walls of the containment tray and hook and loop orother hand-operated fasteners are used to advantage to provide easyassembly and disassembly of the containment device without tools by oneperson.

In other aspects handholds may be provided to enable ease of positioningthe containment device and reinforcement gussets are provided at highstress portions of the containment device for durability.

In another aspect the containment tray, following removal of thebolsters, may be folded and rolled into a compact cylindrical packagefor transport, storage, and reuse. Further, the individually sleevedbolsters may be stacked for transport, storage, and reuse.

Accordingly there is also provided a method for supporting the sidewalls of a portable drip containment tray, comprising the steps ofenclosing each one of a plurality of resilient bolster members within achemically resistant fabric sleeve to form reusable bolster segments;attaching at least one wing flap to the perimeter of the tray along eachside thereof and below the side walls and extending outward from theperimeter; wrapping the reusable bolster segments placed end-to-endaround the perimeter of the tray within the wing flaps; and securing theouter edge or end of the wing flaps to an upper edge of the side wall.

In another aspect the method includes the steps of precutting theresilient bolster members to one of a plurality of standardized lengths;surrounding a bolster member with the coated fabric having sufficientexcess width and length to permit gathering the excess width to create aside seam and the excess length to form a package wrap end panel at eachend of the bolster member; and enclosing the bolster member within thesleeve to prevent liquids from entering the bolster segment and protectthe bolster members from abrasion or other damage.

In another aspect the method includes the steps of placing the bolstersegments on top of the wing flaps and against the side walls of the trayand lifting said distal edge or end of each said wing flap upward andaround said bolster segment to secure it to said upper edge of said sidewall using the hook and loop or other hand-operated fasteners provided.

In another aspect the method includes the steps of attaching handholds,each anchored to an upper portion of the side walls and which may bedisposed at predetermined intervals around the perimeter of containmenttray.

In other aspects, the method includes the step of enabling assembly andremoval of the bolster segments without tools; and folding and rollingsaid containment tray into a compact package for transport, storage, andreuse; and stacking said bolster segments for transport, storage, andreuse.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates one embodiment of a portable spill containment deviceaccording to the present invention;

FIG. 2 illustrates an assembled bolster segment for use in theembodiment illustrated in FIG. 1;

FIG. 3 illustrates a partially assembled containment device with anassembled bolster segment placed in position against one side wall ofthe tray portion of the containment device of FIG. 1;

FIG. 4 illustrates the containment device with one bolster segmentsecured to a side wall of the tray portion of the containment device;

FIG. 5 illustrates a view of one corner of the containment device frominside the containment device;

FIG. 6 illustrates a first step in assembling a bolster segment;

FIG. 7 illustrates a second step in assembling a bolster segment;

FIG. 8 illustrates a third step in assembling a bolster segment;

FIG. 9 illustrates a cross section view along the longitudinalcenterline of the end of a bolster segment following the third step ofFIG. 8;

FIG. 10 illustrates a fourth step in assembling a bolster segment;

FIG. 11 illustrates a bottom panel of a containment tray according tothe present invention with wing flaps attached to each side of thebottom panel;

FIG. 12 illustrates a view of the underside of the containment tray atone corner depicting a gusset installed to reinforce the corner regionof the containment tray;

FIG. 13 illustrates a view of a corner of the containment tray depictingthe construction of the side walls at the corner thereof; and

FIG. 14 illustrates a containment tray after it has been folded androlled into a compact bundle for transport, storage, and reuse.

DETAILED DESCRIPTION OF THE INVENTION Introduction

A portable drip or spill containment device (also called a containmenttray) is disclosed that provides an advance in the state of the art andcombines low cost, light weight, a minimum of component parts, ease ofportability, storage, installation without tools, and reuse. Unlikeprior art spill containment devices, the containment device designedaccording to the present invention employs flexible side walls supportedby fully deformable, resilient bolsters to permit wheeled vehicles todrive or roll unto the device without manipulation or maneuvering of theside wall structures. The device may be easily assembled anddisassembled without tools, is portable, and may be reused many timesover. When folded and rolled up, the containment tray is portable andcan be carried and installed by one person. The bolster structure isformed of a plurality of resilient bolster segments that are uniform inshape and readily stackable in a small footprint. These modular featuresmake the device easily transported or stored.

The portable containment device or tray may be constructed for any sizevehicle or mobile container by attaching multiple panels of a fuel andchemical resistant fabric together and using as many of the sleevedbolster members (bolster segments) as needed. In most applications asmall number of standard-length bolster segments may be used toconstruct a wide variety of sizes of the containment device. Thecontainment device may generally be any shape, although for mostapplications, a rectangular or square shape is convenient. The design ofthe containment device described herein is readily adapted to othershapes. In some applications, a combination of several containmentdevices used together may be preferred.

The basic containment device comprises a fabric tray having a bottompanel and low profile side walls to retain spilled liquids and debris.The side walls, which are formed as upward extensions of the bottompanel so that liquids are retained, further employ a unique form ofpositive support assembled from a minimum of components and that iseasily installed without tools. The support for the side walls isprovided by an assembly of bolster segments (a bolster assembly)surrounding the containment tray and placed against the outer side ofthe side walls. The bolster segments are fully deformable, so that theymay compress when driven over and readily return to their original shapefollowing compression. To form the bolster segments, resilient bolstermembers are individually enclosed in sleeves to protect them fromabrasion and deterioration from contact with rocks, debris, harshchemicals and the like. The preferred enclosing covering or envelopeshould also be impervious to liquids except for an air vent at the upperportion of each end of the bolster segment to permit air or liquids toescape when bolsters are compressed or to drain liquid that may haveentered within the sleeves. The air vents also permit more rapidrestoration of the resilient bolster material to its quiescent conditionafter being compressed.

Wing flaps, attached to the perimeter of the tray along the undersideedges of the containment tray extend outward from the side wallssufficiently to wrap around the bolster segments and attach to the upperedges of the side walls of the tray, thereby enclosing the bolstersegments and securing them next to the side walls to provide fullsupport of the side walls. The side walls are thus supported andmaintained in a vertical position against collapse to contain asubstantial amount of spilled materials while permitting vehicles todrive over the side walls and bolster members without damage whenentering or leaving the containment device. It is a distinct feature ofthe present invention that no mechanical braces, collapsible orotherwise, or rigid or inflatable members are required to support theside walls of the containment device. Further, the installation and takedown of the bolster components without tools is facilitated by thedesign of the containment device, without impairing it's portability.The illustrated design, which makes use of the well known hook and looptype of fastener, is not limited to such fasteners. For example, snapfasteners or spring clips or laces that may be tied may be suitable,particularly for smaller forms of the containment device describedherein. Wing flaps may be configured to fully enclose the bolstersegments or be configured as narrower flaps that are used at intervalsaround the perimeter of the containment tray yet still sufficient toretain the bolsters in position to support the side walls.

Pull handles, in one example formed by optional loops fabricated ofheavy duty webbing strap, may be attached to the containment device, forexample at each corner of the containment tray for ease of handling andpositioning the tray. Further, the pull handles or loops, for largersizes of the containment device, may be advantageously attached to theside walls at intervals around the perimeter of the containment tray inaddition to or alternatively to the corner placement.

In use, the containment tray portion of the containment device isoriented according to the desired compass with its wing flaps fullyextended. The bolster segments are then placed against the outside ofthe side walls of the containment tray with the hook strips of thebolster segments aligned with and adjacent the corresponding loop stripsdisposed along the outside upper edge of the side walls. After thebolster segments are thus attached to the side walls of the containmenttray, each wing flap is wrapped upward and around the attached bolstersegment and the outer edge or end of the wing flap with the hook stripthere along is folded or wrapped over and attached to the loop strip onthe inside upper edge of the side wall, thus securing the bolstersegment to the side wall to provide a stable wall structure. Thussupported, the bolster assembly prevents the side wall from collapsingor rolling over and diminishing the integrity of the containment device.

One typical example of use of the portable spill containment devicedisclosed herein is at an oil & gas drilling site. Servicing vehiclesmay be driven or rolled on to the spill containment device such that anyspills that may occur from the vehicle or the hoses or containersattached to it will be contained within the area bounded by the sidewalls of the device. The spilled substances may then be removed from thecontainment device without them being absorbed into the surroundingarea. In a second example of use, two vehicles may each be positioned onseparate containment devices. Placement of a vehicle is achieved bymerely driving or rolling upon the containment device and parking it ina central position on the tray. No damage results to the bolsters orside wall when thus deformed because of the compressibility andresiliency of the materials used in the construction of the bolsterassembly. Alternatively, because of the ease with which the containmentdevice may be deployed, the bolster segments for the last side of thedevice may be installed after the subject vehicle or other implement ormachinery is driven or placed on the containment device. The containmentdevice may be used with vehicles of all kinds and mobile containerscontaining materials that may be toxic or harmful to the environment orsurfaces where the vehicle or container is located.

The containment device is portable and reusable: the tray portion(bottom panel and side walls) may be easily folded and rolled into acompact barrel-like package or module, and tied with rope or elasticcords or straps, for storage and transport. The bolster, assembled of aplurality of individually sleeved foam members, called bolster segmentsherein, is readily disassembled from the tray and the individuallysleeved members are readily stacked in a relatively small footprint forstorage or transport. Both the tray portion and the bolster segments arelight weight and easily handled by one person.

The portable containment device disclosed herein is constructed of onlya few low cost materials, all readily available in bulk:liquid-and-chemically impervious tarp fabric, resilient open cell foam,hook & loop or other hand-operated fasteners, webbing strap, and heavyduty thread. Fabrication operations involve cutting, sewing,vulcanizing, and welding (e.g., “heat sealing”), all well within thecapabilities of manufacturers of tarpaulin, tent and awning products,etc.

DETAILED DESCRIPTION

FIG. 1 illustrates one embodiment of a portable spill containment device10 according to the present invention. In the description that follows,dimensions given are for a typical example that is large enough toaccommodate a single unit truck. Containment devices of the typedescribed herein for smaller vehicles such as lawn tractors or mowersmay be scaled appropriately. For larger vehicles such as tractor-traileror five axle rigs, a pair of containment devices such as are describedherein may be used effectively, placed end-to-end. One practical upperlimit to the size of a portable containment device is the ability of oneperson to carry or maneuver a folded and rolled-up tray portion of thedevice as will be described for FIG. 14.

The containment device 10 depicted in FIG. 1 is not drawn to scale inorder to show clearly the components of the device. For example, theplurality of bolster segments 18 that make up the bolster assembly 16may typically be each four or seven feet long and arranged end-to-endaround the perimeter of the containment tray 12. Thus the tray 12pictured in FIG. 1 may be construed to be a square shape about eight orfourteen feet on a side. In practice, a containment device 10 for asingle unit truck would be a rectangle approximately twelve feet wideand twenty-nine feet long. These dimensions are derived from determiningthat a minimum number of bolster segment lengths may be used toaccommodate most sizes of containment devices. One preferred set oflengths for the bolster segment 18 may be, for example, three, four, andseven feet. Other length combinations are, of course, suitable,depending on the applications. In the present illustrative example of a12 ft.×29 ft. containment device 10, one seven foot and one four footlength is used for the shorter side (7+4+2×0.5 feet for the bolstersegment widths) and four each of the seven foot (4×7+2×0.5 feet) lengthsare used for the bolster assembly 16 on the longer side. The tray 12 forsuch a device would be assembled from several sheets of the fabricmaterial with the adjoining edges welded together to form a singleliquid-impervious sheet for constructing the tray 12. See thedescription below for FIG. 11.

Continuing with FIG. 1, the drip pan or tray 12 is preferably formed ofa PVC coated scrim material to form a durable, fuel and chemicalresistant fabric. The fabric in this illustrative example is a PVC(“polyvinyl chloride”) coated polyester scrim material, coated on bothsides, having a rated weight of approximately 18 oz per square yard (18oz./yd.²) and found suitable for the application illustrated herein asshown herein. While lighter weight coated fabric materials may be used,it is suggested that weights below 14 oz./yd.² be avoided to ensuresufficient durability. The lighter weight materials may be adequate forsmall items weighing a few hundred pounds (lb.) or less such as lawnmowers, and the like. Heavier weight materials—e.g., up to approximately24 oz./yd.²—may be used but it has been found that the advantages ofgreater weights diminish beyond the 18 oz./yd.² figure. Further, andimportantly, the 18 oz./yd² specification has been found to provide anoptimum balance between portability and durability. Other materialsconsidered in development of the present embodiment included canvas(which absorbs moisture making it subject to mildew and rot), coatednylon (which dissolves in the presence of hydrochloric acid), andpolyethylene or polypropylene (which lack durability). The PVC coatedpolyester in this example is a woven polyester fabric having a threadcount of 18×17 (warp and fill), is UV (ultraviolet radiation) resistant,and has a usable temperature range of −40° F. to 180° F.

Continuing with FIG. 1, the drip pan or tray 12 is preferably formedwith side walls 14 supported on all sides by a compressible foam corebolster assembly 16 made up of bolster segments 18. The bolster segments18 are preferably enclosed in sleeves made from the same PVC coatedfabric. The containment device 10 may be sized to accommodate anythingfrom a vehicle as small as a lawn mower to a large industrial vehicle.The vehicle or other implement or machine or storage vessel ispositioned upon it such that the side walls 14 are outside the perimeterof any projection on the ground of the vehicle or other item that mightleak. In the preferred embodiment, the bolster segments 18 are rigidenough to fully support the side walls 14 but compressible enough to bedriven over as the vehicle is driven or rolled into position on the trayportion of the containment device 10. Also shown in FIG. 1 are handholds74 to be described with FIG. 4 herein below.

Persons skilled in the art will recognize that the principles of thepresent invention illustrated by the embodiment shown and described inthe drawings are readily adaptable to a wide variety of sizes and shapesof the containment device depicted herein. For example, the containmenttray 12 may be round, oval or other shapes to suit the particularapplication. Likewise, the bolster segments 18 may be stacked to providefor the support of higher side walls 14 of the containment tray 12. Onejustification for the use of stacked bolster segments in such cases isthat it is generally more efficient to make a small number ofstandard-sized bolster segments. Further, bolster segments of the sizesdescribed herein are relatively small and light weight to facilitateease of handling. All of these variations are contemplated as beingwithin the scope of the invention as claimed.

FIG. 2 illustrates an assembled bolster segment 18 for use in theembodiment illustrated in FIG. 1, after the foam core bolster member 30(See FIG. 6) is wrapped in the PVC coated fabric and prior to attachmentto the tray portion 12 of the containment device 10. The bolster member30, which functions as a core of the bolster segment 18, may preferablybe formed of a precut length (seven feet in this example) of a solidcore, open cell polyurethane foam having a density of approximately 1.8lb/ft³ and an indentation force deflection of approximately 90 lb. Thesefigures may be varied somewhat. For example, the 1.8 lb/ft³ is againchosen for a suitable balance between the weight of the bolster segment18 and factors such as its durability and ability to maintain support ofthe side wall 14 of the containment tray 10. However, this nominalfigure may be varied with satisfactory results within the range ofapproximately 1.4 to 2.2 lb/ft³. Similarly, the indentation forcedeflection requirement may be varied within the range of 70 lb. to 110lb. It is even possible that, in certain applications, for the densityand indentation force deflection values to be suitable outside theserecommended ranges without departing from the utility and principlefeatures of the present invention.

Open cell foam is chosen for the bolster members 30 because, whencompressed, the air in the cells of the foam escapes by passing fromcell-to-cell, allowing the body of the foam to occupy less space. As thecompressing agent is removed, air seeps back into the foam cells,causing the cells to expand back to their original size and shape. Solidfoam material is preferred, as opposed to hollow bolster members,because it provides maximum support of the side walls 14 yet is stillfully compressible. Further, the foam core bolster member 30 should haveat least two adjoining sides meet at a right angle and have a widthdimension of approximately the same size as the height of the side wall14 of the containment tray 12. For example in a typical largecontainment device 10 a side wall 14 height of six inches is suitable.Thus the cross section of the bolster member 30 may be a right triangleor a rectangle having at least one six inch side or it may be cut tohave a square cross section six inches square. The right anglepreference is mentioned in the preceding discussion because it isadvantageous to support the side walls 14 in a vertical orientation toprovide optimum performance of the containment device 10. In otherapplications, where taller side walls 14 are need, side walls 14 ofeight, ten, or twelve inches may be used. In such cases, the bolstermembers 30 may be sized in single units or multiple unit configurations.The bolster assembly 16 in cases using multiple bolster segments 18 maybe stacked as mentioned previously.

The fabric sleeve 20, which encloses the bolster member 30 and preventsdamage that may occur due to fuel, chemical or other materials coming incontact with the polyurethane foam material, is preferably fabricatedfrom the same PVC coated polyester scrim material used for thecontainment tray 12. The sleeve 20 is also able to protect the foambolster member 30 from the abrasion likely to occur from debris and whenthe wheels of a vehicle pass over the bolster assembly 16 portions ofthe containment device 10.

The exemplary embodiment of the invention described herein includes theuse of hook and loop fasteners to secure the parts of the containmenttray 12 and bolster assembly 16 together. The two components of the hookand loop fastener material are referred to herein as a first type and asecond type. The first type may be referred to as the hook configurationand the second type as the loop configuration, although these referencesmay be reversed without changing the meaning of the description, it onlybeing necessary that the fastening operation is accomplished by pressingone type against the other type in any given act of fastening the twotypes together.

Continuing with FIG. 2, a narrow strip of fabric, flap 22 extending fromthe top side of the bolster segment 18 along the length thereof includesa strip of a first type 24A of a two-piece hook and loop fastenerrunning along the length of the bolster segment 18. This first type 24Afastener (for example, the hook type) is preferably used to secure thebolster segment 18 to a respective strip of second type 24B (thecomplement, i.e., the loop type) of hook and loop fastener disposedalong the upper portion of the side wall 14 as will be described forFIG. 3. The hook and loop fastener is chosen in this example for itsdurability, its ability to hold components to be joined securely, andfor its ease of use without tools. Other fastening mechanisms thatprovide detachability without the use of tools to retain all theadvantages of the invention may be selected in certain applications. Thefirst 24A and second 24B hook and loop strips are used to attach thebolster segment 18 to the side wall 14 such that the side wall 14 issupported to its full height when installing the bolster segment 18.This feature ensures that the side walls 14 of the containment deviceare fully supported to best contain any substances deposited upon it.

Also shown in FIG. 2 is a view of a finished end 26 of a bolster segment18 after the material of sleeve 20 has been trimmed, gathered, foldedand stapled or sewn to form a package wrap as will be described in FIGS.6-10 herein below. The package wrap provides a barrier to liquids, yetprovides for venting of air along its upward edge as will be described.The finished end 26 includes a folded and sewn flap 28 as shown. Bothends of the bolster segment 18 are finished in the manner shown. Theedge of the bolster segment 18 with the flap 28 is intended to bedisposed upward when installed next to a side wall 14.

FIG. 3 illustrates a partially assembled containment device 10 with anassembled bolster segment 18 positioned against one side wall 14 of thetray portion 12 of the containment device 10 of FIG. 1. The bolstersegment 18 is preferably attached to one side of the tray portion 12 ofthe containment device 10 using the first 24A and second 24B types ofthe hook and loop fastener previously described. The tray portion 12 ofthe illustrated embodiment is constructed of a single piece (or a sheetformed of several pieces) of the same 18 oz. PVC coated polyester fabricused to wrap the foam bolster cores 30. The tray side walls 14 areformed by turning up the outer edges 70 of the tray material 82 as willbe further described for FIGS. 12 and 13. At the corners 60, thetriangular, folded corner 94 of the fabric is pressed together andfolded around the corner 60, then secured to the adjacent side wall 14by stitching 96 and/or vulcanizing, or welding or heat sealing. Thisjoint is provided at each corner 60 to provide a liquid-proof containertray 12. The height of the side wall 14 may typically be approximately 6inches, although other heights in the range between 4 and 12 inches maybe preferable for some applications as previously described.

Extending under the wrapped bolster segment 18 on each side of the trayportion 12 of the containment device 10 is a wing flap 62 (alternatelycalled an extension flap 62 herein) of a predetermined width. In thisexemplary case this width measured from the bottom of the side wall 14at the perimeter of the containment tray 12 may be slightly greater (byapproximately 3½ inches) than ¾ of the perimeter dimension of the crosssection of the wrapped bolster segment 18. In other words, if thebolster core 30 has a square cross section of 6 inches×6 inches, thecross section will have a perimeter of 24 inches. The wing flap 62 willwrap around three of those four sides (or 18 inches) of the sleevedbolster segment 18 and must also have about 4½ inches of additionalspace to allow about one inch for sealing or sewing the wing flap'sinner edge to the underside of the tray 12 and about 3½ inches along theouter edge of the wing or extension flap 62 to accommodate a strip ofone of the first 24A and second 24B types of a hook and loop fastener.These dimensions are approximate and may vary in practice or withparticular applications. Thus the predetermined width of the wing flap62, measured from the side wall 14 of the tray 12 after being attachedthereto is approximately 20¼ inches in this example. Before attachmentto the tray 12 the total width of the wing flap 62 should beapproximately 22½ inches. As further described in FIG. 11 the inner edge(about one inch wide) of the extension flap 62 is attached to the trayportion 12 at a point about seven inches in from the outer edge 70 ofthe wing flap (which would be just below the side wall 14 when the tray12 is completed) by first vulcanizing the two parts together and thenapplying stitched seams (See FIG. 5) along the portions of the jointthat are in contact.

Persons skilled in the art will recognize that the dimensions given areexemplary and intended as a guide to the construction. Scaling thedimensions of the components of the containment device is of coursecontemplated to adapt to particular circumstances such as the overallsize of the containment device 10, the cross section dimensions of thefoam core material used in the bolster segments, the width of the stripof hook and loop or other type of fastener employed, etc.,considerations that may come into play for constructing smaller versionsof the containment device 10. Moreover, as mentioned elsewhere herein,the wing flaps may be configured to fully enclose the bolster segmentsor be configured as narrower flaps that are used at intervals around theperimeter of the containment tray yet still sufficient to retain thebolsters in position to support the side walls.

Continuing with FIG. 3, the extension flap 62 on each side of thecontainment device 10 also includes a strip of a first type (hook) 68Aof a hook and loop fastener sewn along its outer-most edge 66 aspreviously described. This first type 68A of hook and loop fastener isused to secure the outer edge of the wing flap 62 to a correspondingcomplement type strip—e.g., a second type (loop) 68B—of hook and loopfastener located near the top edge 70 on the inside of the side wall 14of the tray portion 12 of the containment device 10. After the bolstersegment 18 is placed next to the outside of the side wall 14, theextension or wing flap 62 is wrapped around the bolster segment 18 andits edge 66 pressed against the inside of the top edge 70 of the sidewall 14 to activate the first 68A and second 68B strips of the hook andloop fastener together. This step, shown completed in FIG. 4, securesthe bolster segment 18 to the side wall 14 and supports the side wall 14to maintain the integrity of the containment device 10 for its intendedpurpose, to contain any spills within the containment tray 12 that fallupon it. The bolster assembly 16 provides stability for the side walls14 even when driven over by vehicles or stepped upon by workers. Thisstability is an important attribute of the invention for containing anyliquids spilled or otherwise deposited upon the containment device. Itmay be recognized that the second type hook and loop material used forthe fasteners 24B and 68B may be formed by a single four-inch wide stripof the second type (loop) of hook and loop fastener material by foldingit lengthwise over and along the upper edge 70 of the side wall 14 andstitched to the side wall 14 with the same size 138 bonded thread usedelsewhere.

FIG. 4 illustrates the containment device 10 with the bolster segment 18secured to the one side wall 14 of the tray portion 12 of thecontainment device 10. Also visible in FIGS. 3, 4 and 5 is a handhold74, a loop that is secured to the upper portion 70 of the side wall 14at or near the corner 60. In one embodiment the handhold 74, made ofheavy webbing strap approximately 2 inches wide, is secured between theinside of the upper edge 70 of the side wall 14 and either the secondtype 24B or 68B strip of the hook and loop fastener material by the samesewn seams 64 that secure these components together. If a single pieceof hook and loop material folded in half lengthwise (one half on eitherside of the upper edge 70 of the side wall 14) is used for both 24B and68B a slit may be made along the position of the fold between the twohalves thereof and the two ends of the webbing strap loop inserted therebetween before securing with sewn seams. In other embodiments a handhold74 may be similarly anchored to a side wall and located in at least oneposition anywhere around said containment tray. A plurality of handholds74 may be positioned at intervals around the perimeter of thecontainment tray. Handholds 74, whether several are used or only one isused, may alternatively be installed either along the upper edge of theside walls as described or at other locations.

The webbing strap should be cut to a length of approximately 15 inches,doubled to form a loop 7½ inches long and sewn together with type 138bonded thread at the ends for about two inches from the ends, forming aloop about five to 5½ inches long. The sewn end of the loop is theninserted through a slit in the folded second type (loop) material 24B,68B along the upper edge 70 of the side wall 70 at each corner 60 of thecontainment device, and sewn again with the type 138 bonded thread. Aplurality of such handholds 74 may similarly be placed at variousintervals around the side wall 14 of the containment device 10,preferably at the corners of the containment device 10, to facilitatehandling it as it is moved about during set up or repositioning. Anotherfeature of the illustrated embodiment of the present invention is thedetail shown at the corner 60 (same for all corners), including thefolded corner flap 94 and the sewn seam 96 that secures the flap 84 tothe side wall 14 as will be further described with FIG. 13 herein below.

FIG. 5 illustrates a view of one corner 60 of the containment device 10from inside and just above the tray portion 12 of the containmentdevice. Clearly visible are the outer edges 66 of the wing flaps 62secured to the inside of the side walls 14 at their upper edges 70 usingthe first 68A and second 68B hook and loop fasteners as described. Thussecured, the side walls 14 are shown supported by and against thebolster segments 18 (not shown in FIG. 5 but understood to be enclosedwithin the extension flaps 62). The tray 12 and extension or wing flaps62 of the containment device may be sewn together along seams 64 usingsize 138 bonded UV-inhibited polyester thread in a single needle lockstitch, for example. This thread may also preferably be used to sewother seams in constructing the containment device such as the first andsecond hook and loop fastening strips to their respective flaps and sidewalls, etc.

FIGS. 6 through 10 illustrate the steps for fabricating the bolstersegment 18 shown and described in the foregoing figures. The bolstersegment 18 incorporates a number of features that contribute to theutility of the invention. The material used for the bolster members is aresilient, open cell urethane foam product having a preferred density ofapproximately 1.8 lb. per cu. ft. and an indentation force deflection of90 lb. in this illustrative example. These are nominal values found tobe effective during experimentation but may be varied to suit particularapplications. For example, these nominal values may be varied withsatisfactory results within the range of approximately 1.4 to 2.2 lb/ft³and 70 lb. to 110 lb. respectively. Open cell foam is selected becauseit is fully resilient when compressed, returning to its original shapeafter the compressing agent is removed. For example, as the wheels of avehicle roll over the bolster assembly 16 air in the cells of the foamescapes by passing from cell-to-cell, allowing the body of the foam tocompress. As the compressing agent is removed, air seeps back into thefoam cells, causing the cells to expand back to their original size andshape. The density of the foam and the indentation force deflectionspecifications are chosen to facilitate these properties of the bolstercores to function as intended in this application. Closed cell foamwould not ordinarily be suitable for the bolster cores 30 because theclosed cells would burst under compression and would not expand back totheir original size and shape, thus reducing the resiliency and usablelife of the bolster segments.

FIG. 6 illustrates a first step in assembling a bolster segment 18. Inthis example, a bolster core 30 is seven feet long and has a squarecross section six (6.0) inches on a side. In other embodiments the crosssection could be a right triangle six (6.0) inches on the two adjacentsides and having a hypotenuse of slightly less than 8.5 inches in theillustrated example. While the latter could save somewhat on the amountof coated fabric material need for the wing flaps 62 and couldconceivably function as intended, it would have less durability than thesix-by-six inch cross section because there would be less foam corematerial in the upper region of the bolster segment to support the sidewall 14 structure of the containment device 10. In typical containmentdevices for use with trucks it is recommended that the bolster corecross section be at least six inches high, six inches wide at its base,and at least 3 inches wide across its upper side. Preferably, the crosssection of the bolster segments will be a shape selected from the groupconsisting of a right triangle, rectangle, square, or otherquadrilateral having at least one right angle corner. In practice,because of ease of manufacturing, foam core “sticks” having a squarecross section may be the most economical as compared with sticks havingother cross sections. Smaller cross sections for small containmentdevices may be suitable. Bolster member cores having a round crosssection have the disadvantage of being unable to support the side wallsin a fully vertical orientation, although their use in some applicationsmay be satisfactory.

To form a bolster segment 18, the bolster core 30 is wrapped in a pieceof the same PVC coated fabric described herein above to form a sleeve 20that, for the illustrated example, is cut to approximately 20 incheslonger then the five foot length of the bolster core 30, and aboutfour-and-a-half inches wider than the length of the perimeter of thecross section of the bolster core 30. Note that for bolster membershaving heights greater than 6 inches, the excess fabric extending pasteach end will be approximately the height of the bolster core 30 plusfour inches to allow sufficient material to form the package wrap to bedescribed. For example, an eight inch high bolster core 30 will requireabout 12 inches excess length of the PVC fabric at each end.

Continuing with FIG. 6, generally, the hook and loop material 24A may besewn together with the edges of the flap 22. Both long edges of thefabric sleeve 20 material are brought together and a strip of the firsttype 24A of the hook and loop material is positioned along it and sewnthereto along each edge of the hook and loop strip at the locationindicated by the dashed lines 31 with size 138 bonded polyesterUV-inhibited thread in a double needle lock stitch. This doublethickness of material and the double needle stitch completes theoperation in one pass through the sewing machine. It also may provideadditional strength to reinforce the edges of the containment tray whenit is dragged over the surface of the ground to position it in thedesired location. In practice, the preferred process is to form thesleeve 20 first and then insert the foam core 30 into it from one end ofthe sleeve 20. This also facilitates the sewing operation, and is thereason that the circumference of the sleeve 20 is made slightly largerthan the perimeter of the bolster member 30.

After the sleeve 20 is formed, and the foam core bolster member inposition within the sleeve 20 leaving about 10 inches of excess sleevelength extending from each end of the foam core 30, several cuts may bemade in the excess length of the coated fabric sleeve 20. These cuts,shown in FIGS. 6 and 7, facilitate forming a “package wrap” end panelfor the sleeve 20. The package wrap will fully enclose the foam core 30.In a first step, the excess length 32 of the sleeve 20 is cut througheach upper corner along the dashed lines 34, to a depth just to the endof the foam core 20. The flap 38 created by the two cuts 34 is foldedback over the upper surface of the sleeve 20. In a second step a cut 35is made aligned just outside the inner-most of the pair of sewn seams 31from the end of the sleeve 20 to the end of the foam core 30 to separatethe strip of fabric with the hook and loop strip 24A sewn to it from therest of the excess length of the sleeve 20. In a third step a pair ofcuts 36 is made in the sleeve, which are angled across the upper cornersas shown in FIG. 7. This removal of excess material facilitates formingthe package fold as will be described.

FIG. 8 illustrates a third step in assembling a bolster segment 18, thefolding of the excess length 32 to form a “package wrap” end panel 26for the bolster sleeve 20 to fully enclose the bolster core 30, thusproviding a barrier against liquids from entering inside the sleeve 20.The package wrap forms the end panel 26 that seals the entire end of thebolster segment 18 except the two upper-most corners of the end panel26. Thus, the end panel 26 will not leak unless the bolster segment 18is turned on its side. In that orientation any liquid that may haveentered inside the sleeve 20 will drain from the lowest-disposed uppercorner because the upper corners are purposely not sealed. To form thepackage wrap, the two sides 40, 42 are folded inward toward each otherwhile lifting the bottom portion of the excess length 32 (FIG. 7)against the end of the bolster core 30. The free end of the excesslength 32 can then be folded over a gathered fold of the flap 38 andstapled with several staples 44 as shown in the cross section view ofFIG. 9 to form the flap 28. This flap 28 secures the sleeve material toform the end panel 26. In a later step, the flap 28 is sewn along theline of staples with the type 138 bonded thread to permanently securethe flap 28 and the excess of the flap 38 and the free end 50 aretrimmed and discarded. The free end 50 is trimmed along the dotted line52 as shown in FIG. 10.

FIG. 11 illustrates a bottom panel 82 of a containment tray 12 accordingto the present invention with wing flaps 62 attached to and extendingfrom each side of the bottom panel 82. The bottom panel 82 is shownsegmented at the dashed lines to indicate that various sizes of thecontainment tray may be formed using the same construction andcomponents, merely scaling the dimensions to provide whatever size isneeded. Persons skilled in the art will realize that in practice only afew sizes of the components may be adapted to form a wide variety ofsizes and shapes of the drip containment device described herein. Theinward edge of each wing flap 62 may be welded or heat sealed and sewn(using the same type 138 bonded thread as in previous steps) to theunderside of the bottom panel 82 by vulcanized seams 86 spaced adistance=side wall height+one inch away from the edge of the bottompanel 82 material (which is the same as the upper edge 70 of the sidewall when the containment tray 12 is formed). In this example, the seamattaching the wing flap 62 to the bottom panel 82 is seven inches inwardfrom the edge 70. Other methods of securing the extension flaps 62 tothe containment tray 12 may be used as long as a liquid-impervious jointhaving the required mechanical strength is provided.

Continuing with FIG. 11, for smaller containment devices the bottompanel 82 may be a single piece of the PVC coated fabric describedpreviously. Typically, however, the bottom panel 82 is formed of severalpieces using vulcanized seams 86 such as those used to attach the wingflaps 62 to the bottom panel 82. A seam vulcanizing machine well knownin the art may be used. A seam formed in this manner provides a highresistance to sheer forces (in the plane of the fabric panel at rightangles to the seam) but lesser resistance to tearing forces (forexample, pulling two ends of a seam away from each other and away fromthe plane of the panel). For instance, to form a containment tray 12 fora containment device 10 of twelve feet by twenty-nine feet in thisexample, three lengths of the coated fabric cut from a standard roll 61inches wide are needed. The three lengths are then placed side by sidewith just enough overlap—typically about one inch—at the adjoining edgesfor a seam to be vulcanized or welded.

FIG. 12 illustrates a view of the underside of the containment tray 12at one corner 60 thereof depicting a gusset 90 installed to reinforcethe corner region of the containment tray 12. The gusset 90 reinforcesthe corner structure of the containment device 10 and is especiallyhelpful when a pull handle 74 is attached at the corners 60 thereof. Thegusset 90 may be attached by a thermal weld at least in the region 90(and preferably over its full area).

FIG. 13 illustrates a view of a corner of the containment tray depictingthe construction of the side walls 14 at the corner 60 thereof. Thecorner is formed by gathering the side wall 14 material and folding thetriangular shape 94 thus formed against one of the side walls 14adjacent the corner 60, where the triangular shape may be temporarilystapled until it can be sewn along at least two lines parallel to theupper edge of the side wall as indicated by the dashed lines 96.

FIG. 14 illustrates a containment tray after it has been folded androlled into a compact bundle 98, and secured with a rope 100 fortransport, storage, and reuse. In place of the rope 100 an elastic cordor belt may be used. In the illustrated example, of a 12′×29′containment device, the bundle 98 and the rope 100 together will weighapproximately 65 lb. and the bolster segments (ten each of the 7 footlength and two each of the 4 foot length) together weigh approximately35 lb. for a total weight of approximately 100 lb. This demonstrates theready portability of the containment device 10 according to the presentinvention.

CONCLUSION

While the invention has been described in detail in only one of itsforms, it is not thus limited but is susceptible to various changes andmodifications without departing from the spirit thereof. Many of thesevariations are mentioned in the foregoing detailed description. Thealternatives mentioned are provided to illustrate useful variations butnot intended to limit the invention to specific embodiments. Forinstance, the materials selected for the illustrated embodiment may bevaried to accommodate particular applications without departing from thespirit of the invention as set forth in the claims. Other examples ofvariations are the number and location of handholds, the height of theside walls, the shape of the containment device, the type of fastenersused to secure the wing flaps to the upper edge of the side walls, thenumber and sizes of the bolster segments, etc. Wing flaps may beconfigured to fully enclose the bolster segments or be configured asnarrower flaps that are used at intervals around the perimeter of thecontainment tray yet still sufficient to retain the bolsters in positionto support the side walls. Moreover, while the apparatus describedherein is named a portable drip containment device for use under avehicle, the device may have numerous other uses even though it'sconstruction falls within the scope of and the recitations in theclaims. Any application requiring a spill-containing tray may be readilysatisfied by using a device as claimed and described herein. The novelcombination of the compressible and reusable bolsters used to fullysupport the side walls of the tray that may be repeatably secured to ordisassembled from the containment tray without tools and the convenientportability of the device for transport and storage provide utility notheretofore available.

The invention claimed is:
 1. A method for removably securing deformablebolster segments adjacent upward-extending side walls of a dripcontainment tray, comprising the steps of: forming a deformable bolstersegment from a resilient synthetic foam; placing said deformable bolstersegment adjacent an upward-extending side wall of the drip containmenttray; wrapping at least one flap extending from the drip containmenttray around the deformable bolster segment; and attaching the at leastone flap to an upper edge of the adjacent side wall to enclose thedeformable bolster segment and support the side wall.
 2. The method ofclaim 1, wherein the step of forming comprises the step of: fashioning abolster core from the synthetic foam wherein the bolster core has across section having four sides and at least one right angle.
 3. Themethod of claim 1, wherein the step of placing comprises the step of:positioning the bolster segment adjacent the upward-extending side wallsuch that a right angle along one edge of the bolster segment isdisposed proximate a lower edge of the upward extending side wall. 4.The method of claim 1, wherein the step of wrapping comprises the stepof: providing at least one flap along each of the upward-extending sidewalls of the drip containment tray.
 5. The method of claim 1, whereinthe step of wrapping comprises the step of: providing a plurality of theat least one flap spaced at intervals around the perimeter of the dripcontainment tray.
 6. The method of claim 1, wherein the step ofattaching comprises the step of: attaching at least one portion of afastening mechanism to the at least one flap and a second portion of thefastening mechanism to the upward-extending side wall; wherein thefastening mechanism is selected from the group consisting of a hook andloop fastener, and a spring clip, a lace, a cord, and a combinationthereof.
 7. The method of claim 1, further comprising the step of:enclosing the deformable bolster segment within a sleeve formed of achemically resistant fabric.